| In order to improve the safety of cigar tobacco leaves,improve the conversion of nicotine in cigar tobacco leaves,and reduce the content of TSNAs in tobacco leaves,a field trial system was set up in Shifang,Sichuan from 2018 to 2021 to study the improvement of nicotine conversion through variety improvement and the reduction of TSNAs content.The main research results are as follows:1.1)All cigar varieties had the problem of nicotine to nornicotine conversion at different degrees.16 cigar varieties had nicotine contents in the range of 1.14%to 5.42%,averaging 3.02%;and nornicotine contents changed in the range of 0.11%to 1.47%,averaging 0.40%.The nicotine conversion rate ranged from 5.03%to 53.12%with the average of 12.66%,and the variation coefficient of nicotine conversion among varieties being as high as 101.01%.2)The average nornicotine content and nicotine conversion rate of cigar wrapper varieties were significantly higher than those of cigar filler varieties.3)The content and proportion of TSNAs in tobacco leaves of different cigar tobacco varieties were significantly different.The variation range of total TSNAs content was 181.74～7759.1 ng/g,with an average of 3010.98 ng/g.The content of NNN was the highest with the average value of 1616.59 ng/g,and the variability was also the highest,with the coefficient of variation being 97.28%.4)Correlation analysis showed that there was a significant positive correlation between nomicotine content and NNN and TSNAs content in 16 cigar tobacco varieties tested,with the correlation coefficient between NNN and nornicotine content being 0.802.[Conclusion]The high level of nornicotine content resulted from nicotine conversion was one of the main cause of increased formation and accumulation of NNN and total TSNAs in cigar tobacco leaves.2.1)The distribution of alkaloids among different cigar varieties was significantly different,and the variation of nicotine and nicotine in Shiyan 1 was the largest.2)Among the main cultivar,Dexue 5 had the highest total alkaloid content,followed by Shiyan 1.3)Dexue No.4 had the lowest proportion of non-transformed plants,while Dexue No.5 had the highest proportion of transformed plants.No non-transformed plants were found in the selected samples.4)The total TSNAs content of Shiyan No.1 was the highest,which was 3045.39ug/g,while that of Dexue No.7 was the lowest.[Conclusion]There were significant differences in the distribution of nicotinic conversion among different cigar varieties.3.The content of nicotine in the modified varieties Dexue 4,Dexue 7 and Shiyan 1 was significantly lower than that in the control group,and the conversion rate of nicotine in the modified varieties was significantly lower than that in the control group.The total contents of NNN and TSNAs in improved varieties were significantly lower than those in control varieties.The ratio of NNN to TSNAs of improved varieties was significantly lower than that of control varieties,and the ratio of NAT to TSNAs of improved varieties was significantly higher than that of control varieties.The contents of total sugar,nicotine and reducing sugar in improved varieties were higher than those in control varieties.The ratio of reducing sugar to total sugar and the ratio of reducing sugar to nicotine of modified species were higher than those of control species.The scores of style,aroma temperament,aroma quantity,concentration,miscellaneous gas,vigor,irritant and aftertaste of modified varieties were higher than those of control group. |
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